There is no area code 823 in North America (country code +1 = USA, Canada, etc.).
Country code +82 is South Korea.
Either you received a call from South Korea, or the caller ID was incorrect, either because valid data got mangled on its way to you or because a telemarketer or scammer sent fake caller ID data.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
The country code and area code of Salamanca, Spain is 34, 823.
The country code and area code of Kinmen, Taiwan is 886, 823.
The country code and area code of Killa Saifullah, Pakistan is 92, (0)823.
The country code and area code of Aki District- Hiroshima, Japan is 81, (0)823.
The country code and area code of Changhua, Taiwan is 886, 47.
The country code and area code of ChillÌÁn, Chile is 56, 42.
If you are calling to a land line: +52 (Area code, i.e. 55 = Mexico City) (Phone Number): +52 55 12345678 If you are calling to a cellular phone +52 1 (Area code, i.e. 55 = Mexico City) (Phone Number): +52 1 55 12345678
The country code and area code of Asturias, Spain is 34, 884.
The country code and area code of Gelephu, Bhutan is 975, 6.
The country code and area code of Baghdad, Iraq is 964, 1.
The country code and area code of Arganil, Portugal is 351, 235.
The country code and area code of Alava, Spain is 34, 845.